Fluid pressure system



June 30, 1953 M. G.- CARLSON FLUID PRESSURE SYSTEM Filed Dec. 8, 1951 QN NN Mam 07. mm

Hm. QIN\\ Patented June 30, 1953 FLUID PRESSURE SYSTEM Melvin G. Carlson,

Chicago, Ill.,

assignor to Goodman Manufacturing Company, Chicago, Ill., a corporation of Illinois Application December 8, 1951, Serial No. 260,740

9 Claims.

This invention relates generally to fluid pressure systems employing a pair of pumps for supplying pressure uid, and more particularly to an improved arrangement wherein the system and the fluid motors connected therein may continue to operate after failure of one of the pumps.

According to the present invention a fiuid pressure system is provided with a pair of fluid pressure pumps, each operating to supply a share of the pressure fluid necessary to operate fluid motors connected in the system. One group of such motors operates at high pressure and high volumes necessary, by way of example, for control of lifting and swinging functions of the gathering and discharge sections of a material gathering and loading machine, and the other group of such motors operates at relatively lower pressures and volumes for the control of the tramming and clutching functions of such a machine. In the invention herein, both of the pumps Supply sufficient fluid for such operations, the output from a rst pump being connected to supply the high pressure, high volume motors, the output from a second pump being apportioned to supply both groups of motors, the system being so designed that upon failure of either pump the pressure fluid is apportioned between both groups of motors, so that continued operation is had, albeit at a somewhat reduced rate, a shuttle or switch-over valve being caused to operate automatically according to failure of one of the pumps.

It is a principal object of this invention to provide a uid pressure system employing a pair of pumps to supply pressure uid, the system being capable of at least emergency operation upon failure of one or the other of such pumps.

Another object is to afford a simple fluid pressure system having a pair of pumps, and wherein the output of one pump is apportioned to different branches of the system, and wherein the output of the other pump may automatically be apportioned to the different branches of the system upon failure of the one pump.

Other objects and important features of the invention will be apparent from a study of the within specification taken with the drawing Which together show a preferred embodiment of the invention and what is now considered to be the best mode of practicing the principles thereof. Other embodiments may be suggested to those having the benefit of the teachings herein, and it is therefore intended that the invention not be limited by the precise embodiment shown nor otherwise than by the scope and spirit of the claims appended to this specification.

The drawing illustrates a preferred embodiment of the invention and shows a fluid pressure system referred to generally by the reference numeral I0, the system including a pump II and a pump I2 connected, as will be shown, to supply pressure uid to a bank of relatively high pressure and high volume fluid motors indicated generally by the reference numeral I3 and to a bank of relatively low pressure and low volume fluid motors indicated by the reference numeral I4.

The bank of high pressure motors I3 comprises double acting motors I6 and I'I and single acting motors I8 and I9 which are controlled respectively by control valves 2l, 22, 23 and 24. The said control valves and their associated motors may be, by way of example, employed for the lifting and swinging functions of the gathering and discharge sections of a material gathering and loading machine.

The bank of low pressure motors I4 comprises double acting motors 26 and 21 and a single acting motor` 28 which are controlled respectively by control valves 29, 3| and 32. The pressure at which uid is admitted to the several motors 26, 21 and 28 is held below a top limit by a pressure relief valve 33 which in the case here may be set at a value of 250 p. s. i.

The output of pump I E is connected by a pressure line 34 to the control valves 2| to 24. The back pressure against the pump II is controlled by a master relief valve 36, set preferably at a value of the order of 900 p. s. i., and connected by a pressure line 3l branching from the output pressure line 34 and having a check valve 38 therein preventing flow back to the pump I I upon failure thereof. The pressure line 34 also has a similar check valve 35 therein, positioned between a pressure responsive valve d@ and the pump Il for preventing flow back to the pump II upon failure thereof and under conditions as will appear as this specification proceeds. The control Valves ZI to 2li, however, are designed to afford substantially little or no resistance to flow of pressure fluid from the pump II when said valves are in the neutral position, thus maintaining the no load back pressure against pump I I at a minimum. The upper limit of back pressure against the pump II upon the operation of the motors I6 to i9 is therefore controlled by the master relief valve 36.

The output from the pump I2 is delivered to a pressure line Il having a check valve 45 preventing flow back to the pump I2 upon failure thereof. The output from the pump I2 is also supplied to a pressure line 62 branching from the pressure line il and connected to the pressure line 34 at a point between the fluid motors I3 and the pressure responsive valve 40, said pressure responsive valve 4U being for a purpose as will appear as this specification proceeds.

The control valves 29, 3l and 32 are designed to aiford substantially no back pressure against the pump I2 when in the neutral position. The pressure relief valve 33 permits only of a maximum working pressure for the uid motors 29, 3I and 32, which has been stated to be of the order of 250 p. s. i. The pressure in the line 4I upon operation of the said motors creates at the same time a back pressure against the pump I2 which back pressure is relieved by the master relief valve 36, there being a line 46 branching from the pressure line 4I and connected to the line 31 connecting with the master relief valve 35.

The quantity of pressure iluid required by the iluid motors I4 is considerably less than that required by the fluid motors I3, and the excess of pressure fluid supplied by the pump I2 is apportioned to the iluid motors I3. To this end the pressure lines 4I and 42 are provided respectively with flow regulating valves 43 and 44; The precise form of these valves is unimportant except as they may be claimed as part of a combination hereof, but in the instant case are designed to give a maximum ow of siX G. P. M. each. It may be noted that each pump is designed to give a flow of eleven G. P. M., and so under condition when the valves 29, 3! and 32 are in neutral position, the flow regulator valve 43 will permit six G. P. M. to be spilled to tank.

The remaining five G. P. M. passes through iiow regulator valve 44 to augment the output of n the pump I I and give a total of sixteen G. P. M. available for the fluid motors I3.

The pumps I I and I2 are thus adapted to supply fluid under pressure to the iiuid motors associated with each as heretofore explained. The pressure responsive valve provides for redirecting of the pressure fluid upon failure of one of the pumps, so that the remaining pump will supply pressure fluid to both tanks of uid motors. The valve 43 comprises a valve body 41 having a bore 48 therein intersected by spaced ports 49 and 52, port 49 being considered as an outlet port and connected to pressure line 34, and port 52 being considered as an inlet port connected to the pressure line 34 to the output of pump I I. A hollow spool valve member 5I is slidable in the bore 48 and is urged in one direction by a spring 53 bottomed at one end within the hollow spool 5I and at the other end on an end cap 54 secured to the valve body 41 in any convenient manner.

A passageway 5G in the end cap 54 bleeds any uid passing the spool member 5I to tank, as shown.

The spool valve member 5I is formed with a piston-like extension 51 opposite from the spring 53. The piston-like extension 51 .rits Within a bore 58 formed in an opposite end cap 59, also secured to the valve body 41 in any convenient manner. A pressure port 6I in the end cap 59 is connected by a pressure line 62 to the output of the pump I2 and between the pump I2 and the check valve 45.

The spool valve member 5I is also formed with end lands G3 and 64 and with a portion 66 between the lands 63 and 64 of diameter less than the diameter of the bore 48, so that when pressure is exerted against the piston extension 51 at the port GI by the pump I2, pressure uid from the pump I I may ow from port 52 to port 49.

Under conditions when both pumps are functioning properly, the pressure responsive valve 40 will be in the position shown in the drawing, the pressure from pump I2 holding the spool member 5I in the position shown, the valve 40 passing uid from pump II to the fluid motors I3. At the same time pump I2 will supply fluid to motors I4, the output from pump I2 being apportioned by the ilow regulator valves 43 and 44 to supply also uid motors I3.

In the event of failure of pump I2, pressure will no longer obtain at the port 6 I and the spool valve member 5I will move by the force of spring 53 to a position lapping the port 49. Under such condition pressure fluid Will be supplied by pump I2 by way of pressure line 46, the fluid being apportioned to the fluid motors I3 and I4 by the flow regulator valves 44 and 43 respectively.

In the event of failure of pump II, pressure fluid will continue to be supplied by pump I2 to both banks of fluid motors, the ow thereto being apportioned by the ow regulator valves 43 and 44. The check valve 38 under such condition prevents by-passing of the flow regulators through the valve 4D, while the check valve 35 prevents the back ilow through the valve 40 which might be effective to operate the pump I I as a motor.

The invention has been described in terms of a preferred embodiment thereof, but it is not intended that the invention be limited by the embodiment herein shown, other embodiments being reserved especially as they fall within the scope and purview of the claims here appended.

What is claimed is:

l. In a fluid pressure system, a fluid pressure motor operable at relatively high volumes, a fluid pressure motor operable at relatively low volume, a pair of pumps for supplying pressure fluid to said motors, a pressure line connecting the output of one of said pumps to said high pressure motor, a pressure line connecting the output of the second of said pumps to said low pressure motor, a branching line from the output of said second pump connected to said rst named pressure line, a flow regulating valve connected in said branching line, a ow regulating valve connected in said second named pressure line between said branching line and said low volume fluid motor, said ow regulating valves apportioning the output from said second pump between said motors, and valve means including a valve body having a bore therein with spaced ports connected in the rst named pressure line, a valve member movable in said bore and subject to pressure from the output of said second pump to unlap said spaced ports for passage of pressure fluid through said valve body from said iirst pump to said high volume motor, said valve member being movable upon failure or said second pump to lap said spaced ports and to pass pressure fluid from the said irst pump to the output side of said second pump to be apportioned between said iluid motors, whilst bypassing said valve means.

2. In a iluid pressure system, a fluid pressure motor operable at relatively high volume, a fluid pressure motor operable at relatively low volume, a first and second pump for supplying pressure fluid to said motors, pressure lines connecting the output of said pumps to said motors, a branching line from the output of the second pump connected to the pressure line from said rst pump, a flow regulating valve connected in said branching line, a flow regulating valve connected in the pressure line from said second pump and between said branching line and said I low volume fluid motor, said flow regulating valves apportioning the output from said second pump between said motors, and valve means having a valve member therein subject to pressure from said second pump and movable to a position under such pressure Where the output of said ilrst pump is connected through said valve to said high volume fluid motor, said valve member being movable upon failure of said second pump to port pressure fluid from the said first pump to the output side of said second pump to be apportioned between said fluid motors.

3. In a fluid pressure system, a fluid pressure motor operable at relatively high volume, a fluid pressure motor operable at relatively low volume, a first and second pump for supplying pressure fluid to said motors, pressure lines connecting the output of said pumps to said motors, a branching line from the output of the second pump connected to the pressure line from said first pump, a flow regulating valve connected in said branching line, a flow regulating valve connected in the pressure line from said second pump and between said branching line and said low volume fluid motor, said flow regulating valves apportioning the output from said second pump between said motors, and Valve means connected in the output pressure line from the first pump and operable upon failure of said second pump to cause the output of said first pump to be diverted to the output side of said second pump and to be apportioned between said fluid motors whilst bypassing said valve means.

4. In a fluid pressure system, a fluid pressure motor operable at relatively high volume, a fluid pressure motor operable at relatively low volume, a first and second pump for supplying pressure fluid to said motors, pressure lines connecting the output of said pumps to said motors, a branching line from the output of the second pump connected to the pressure line from said rst pump, a flow regulating valve connected in said branching line, a flow regulating valve connected in the pressure line from said second pump and between said branching line and said low volume fluid motor, said flow regulating valves apportioning the output from said second pump between said motors, and valve means operable upon the failure of the said second pump to cause the other pump to apportion its output between said fluid motors whilst bypassing said valve means.

5. In a fluid pressure system, a fluid pressure motor operable at relatively high volume, a fluid pressure motor operable at relatively low volume, a ilrst and second pump for supplying pressure uid to said motors, the second of said pumps having ilow regulating valves connected in the output thereof for apportioning its output between said fluid motors, the first of said pumps during normal operation thereof being connected to said high volume fluid motor, and valve means having a valve member therein subject to pressure fromsaid second pump and movable to a position under such pressure where the output of said first pump is connected through said valve to said high volume fluid motor, said valve member being movable upon failure of said second pump to pass pressure fluid from the said first pump to the output side of said second pump to be apportioned between said fluid motors. p

6. In a fluid pressure system, a fluid pressure motor operable at relatively high volume, a fluid pressure motor operable at relatively low volume, a first and second pump for supplying pressure fluid to said motors, the second of said pumps having flow regulating valves connected in the output thereof for apportioning its output between said iluid motors, the first of said pumps during normal operation thereof being connected to said high volume uid motor, and valve means connected in the output of said first pump and operable upon failure of said second pump to cause the output of said flrst pump to be diverted to the output side of said second pump and to be apportioned between said lluid motors.

7. In a fluid pressure system, a fluid pressure motor operable at relatively high volume, a fluid pressure motor operable at relatively loW volume, a flrst and second pump for supplying pressure fluid to said motors, the second of said pumps having flow regulating means connected in the output thereof for apportioning said output between said luid motors, and valve means operable upon the failure of the said second pump to cause the rst pump to apportion its output between said iluid motors.

8. A fluid pressure system according to claim '7 wherein a check valve is connected in the output side of said first pump for preventing said first pump from acting as a motor upon failure thereof by pressure fluid supplied from said second pump.

9. A fluid pressure system according to claim 7 wherein a check valve is connected in the output side of said second pump for preventing said second pump from acting as a motor upon failure thereof by pressure fluid supplied from said rst pump.

MELVIN G. CARLSON.

References Cited in the ille .of this patent UNITED STATES PATENTS Number 

